Ablation, such as radiofrequency (RF) ablation, can be used to treat pathological conditions in situ. For example, ablation can be used to treat a tumor by heating the tumor tissue (e.g., causing cells in the tumor tissue to die). In some instances, tumor ablation can be achieved by inserting an RF electrode having tines at one end into the area of a tumor, deploying the tines, and activating the RF electrode so that RF energy flows through the tines and heats the tumor tissue.